Field of the Invention
The invention relates generally to vehicle suspensions and, more specifically, to variable damping rates in vehicle shock absorbers and forks.
Description of the Related Art
Vehicle suspension systems typically include a spring component or components and a damping component or components. Often, mechanical springs, like helical springs, are used with some type of viscous fluid-based damping mechanism, the spring and damper being mounted functionally in parallel. In some instances a spring may comprise pressurized gas and features of the damper or spring are user-adjustable, such as by adjusting the air pressure in a gas spring. A damper may be constructed by placing a damping piston in a fluid-filled cylinder (e.g., liquid such as oil). As the damping piston is moved in the cylinder, fluid is compressed and passes from one side of the piston to the other side. Often, the piston includes vents there-through which may be covered by shim stacks to provide for different operational characteristics in compression or extension.
Conventional damping components provide a constant damping rate during compression or extension through the entire length of the stroke. As the suspension component nears full compression or full extension, the damping piston can “bottom out” against the end of the damping cylinder. Allowing the damping components to “bottom out” may cause the components to deform or break inside the damping cylinder.
As the foregoing illustrates, what is needed in the art are improved techniques for varying the damping rate including to lessen the risk of the suspension “bottoming out.”